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jakcron
212 lines
8.8 KiB
C++
212 lines
8.8 KiB
C++
/**
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* @file VirtualFileSystem.h
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* @brief Declaration of tc::io::VirtualFileSystem
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* @author Jack (jakcron)
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* @version 0.2
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* @date 2022/02/08
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**/
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#pragma once
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#include <tc/io/IFileSystem.h>
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#include <tc/io/BasicPathResolver.h>
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#include <tc/ObjectDisposedException.h>
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#include <tc/NotImplementedException.h>
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#include <tc/NotSupportedException.h>
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#include <tc/io/DirectoryNotFoundException.h>
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#include <tc/io/FileNotFoundException.h>
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namespace tc { namespace io {
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/**
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* @class VirtualFileSystem
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* @brief A virtual read-only file-system created using a file-system snapshot.
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*
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* @details
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* The intended use-case for VirtualFileSystem is for when the user must read/parse the file-system structures directly instead of using the OS to mount it.
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* The user generates a file-system snapshot from the file-system structures (see @ref VirtualFileSystem::FileSystemSnapshot) and supplies that to VirtualFileSystem to create a IFileSystem shim.
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*
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* User supplies:
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* * a @ref VirtualFileSystem::FileSystemSnapshot struct which contains vectors of directory and file entries, including mapping between absolute tc::io::Path and a dir/file entry.
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* * optionally an implementation of @ref tc::io::IPortablePathResolver to determine the absolute path from a relative path and the current directory. Providing a custom IPortablePathResolver implementation is only required when special logic (like case insensitivity) is required to resolve the correct absolute path.
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**/
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class VirtualFileSystem : public tc::io::IFileSystem
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{
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public:
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/**
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* @struct FileSystemSnapshot
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* @brief A struct which contains vectors of directory and file entries, including mapping between absolute tc::io::Path and a dir/file entry.
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*
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* @details
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* FileSystemSnapshot is snapshot of a FileSystem directory tree. It only has to support read-only access to directory information and file streams.
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*
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* VirtualFileSystem considers a directory to exist if the following conditions are satisfied:
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* * The absolute tc::io::Path to the directory exists in @b dir_entry_path_map
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* * The index from looking up the absolute path in @b dir_entry_path_map is a valid index for @b dir_entries
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*
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* VirtualFileSystem considers a file to exist if the following conditions are satisfied:
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* * The absolute tc::io::Path to the file exists in @b file_entry_path_map
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* * The index from looking up the absolute path in @b file_entry_path_map is a valid index for @b file_entries
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* * The FileEntry in @b file_entries has a @b stream member that is not @b nullptr
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* * The IStream has properties: @b .canRead() == @b true, @b .canWrite() == @b false
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*/
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struct FileSystemSnapshot
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{
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FileSystemSnapshot() :
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dir_entries(),
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file_entries(),
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dir_entry_path_map(),
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file_entry_path_map()
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{
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}
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/**
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* @struct DirEntry
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* @brief This struct contains data for the directory entry.
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* @details
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* This currently contains only a @ref tc::io::sDirectoryListing.
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*
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* DirEntries are used to confirm that a directory exists, and also to provide the sDirectoryListing for getDirectoryListing()
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*/
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struct DirEntry
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{
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tc::io::sDirectoryListing dir_listing;
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};
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/**
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* @struct FileEntry
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* @brief This struct contains data for the file entry.
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* @details
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* This currently contains only a @ref tc::io::IStream pointer.
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*
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* FileEntry objects are used to confirm that a files exists, and also to provide the IStream for openFile()
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* IStream objects should have .canRead() == true AND .canWrite() == false, canSeek() is preferred to be true, but it isn't required.
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*/
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struct FileEntry
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{
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std::shared_ptr<tc::io::IStream> stream;
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};
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/// Vector of directory entries
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std::vector<DirEntry> dir_entries;
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/// Vector of file entries
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std::vector<FileEntry> file_entries;
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/// Mapping of absolute path to index of DirEntry in dir_entries
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std::map<tc::io::Path, size_t> dir_entry_path_map;
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/// Mapping of absolute path to index of FileEntry in file_entries
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std::map<tc::io::Path, size_t> file_entry_path_map;
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};
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/**
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* @brief Default constructor
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* @post This will create an unusable VirtualFileSystem, it will have to be assigned from a valid VirtualFileSystem object to be usable.
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**/
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VirtualFileSystem();
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/**
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* @brief Create VirtualFileSystem
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*
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* @param[in] fs_snapshot The FileSystemSnapshot object which this VirtualFileSystem will use to process file-system requests.
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* @param[in] path_resolver Pointer to @ref tc::io::IPortablePathResolver object that resolves relative paths to absolute paths. If @p nullptr, @ref tc::io::BasicPathResolver will be used.
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*
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* @throw tc::InvalidOperationException @p fs_snapshot Did not contain a root directory entry.
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**/
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VirtualFileSystem(const FileSystemSnapshot& fs_snapshot, const std::shared_ptr<tc::io::IPortablePathResolver>& path_resolver = nullptr);
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tc::ResourceStatus state();
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/// This will release the underlying FileSystemSnapshot and PathResolver
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void dispose();
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/**
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* @brief Create a new file
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* @details This method is not implemented for VirtualFileSystem.
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*
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* @param[in] path A relative or absolute path to file.
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*
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* @throw tc::NotImplementedException This method is not implemented for VirtualFileSystem.
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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**/
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void createFile(const tc::io::Path& path);
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/**
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* @brief Remove a file
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* @details This method is not implemented for VirtualFileSystem.
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*
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* @param[in] path A relative or absolute path to file.
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*
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* @throw tc::NotImplementedException This method is not implemented for VirtualFileSystem.
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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**/
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void removeFile(const tc::io::Path& path);
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/**
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* @brief Open a file
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*
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* @param[in] path A relative or absolute path to file.
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* @param[in] mode One of the enumeration values that determines how to open or create the file. This must be @ref tc::io::FileMode::Open for VirtualFileSystem.
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* @param[in] access One of the enumeration values that determines how the file can be accessed by the @ref IStream object. This must be @ref tc::io::FileAccess::Read for VirtualFileSystem.
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* @param[out] stream Pointer to IStream object to be instantiated.
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*
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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* @throw tc::NotSupportedException Unsupported access/mode ( @p mode was not @ref tc::io::FileMode::Open, or @p access was not @ref tc::io::FileAccess::Read).
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* @throw tc::io::FileNotFoundException File was not found.
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**/
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void openFile(const tc::io::Path& path, tc::io::FileMode mode, tc::io::FileAccess access, std::shared_ptr<tc::io::IStream>& stream);
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/**
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* @brief Create a new directory
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* @details This method is not implemented for VirtualFileSystem.
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*
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* @param[in] path A relative or absolute path to directory.
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*
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* @throw tc::NotImplementedException This method is not implemented for VirtualFileSystem.
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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**/
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void createDirectory(const tc::io::Path& path);
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/**
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* @brief Remove a directory
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* @details This method is not implemented for VirtualFileSystem.
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*
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* @param[in] path A relative or absolute path to directory.
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*
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* @throw tc::NotImplementedException This method is not implemented for VirtualFileSystem.
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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**/
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void removeDirectory(const tc::io::Path& path);
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/**
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* @brief Get the full path of the working directory
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* @param[out] path Path object to populate.
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*
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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**/
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void getWorkingDirectory(tc::io::Path& path);
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/**
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* @brief Change the working directory
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* @param[in] path A relative or absolute path to directory.
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*
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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* @throw tc::io::DirectoryNotFoundException Directory was not found.
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**/
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void setWorkingDirectory(const tc::io::Path& path);
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/**
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* @brief Get directory listing a directory
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* @param[in] path A relative or absolute path to directory.
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* @param[out] info The sDirectoryListing object to populate.
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*
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* @throw tc::ObjectDisposedException Methods were called after the file-system was closed.
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* @throw tc::io::DirectoryNotFoundException Directory was not found.
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**/
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void getDirectoryListing(const tc::io::Path& path, tc::io::sDirectoryListing& info);
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private:
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static const std::string kClassName;
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FileSystemSnapshot::DirEntry* mCurDir;
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FileSystemSnapshot mFsSnapshot;
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std::shared_ptr<tc::io::IPortablePathResolver> mPathResolver;
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};
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}} // namespace tc::io
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